There are lots of different ways to "network" 2 PCs so no simple answer.
Do you just want them connected to each other with no other connection (internet for example)
Or do you want them both to be able to use the one internet connection, AND share files between each other.
Do you also want them to share one printer.
If you have Windows XP on either machine then go into the help and type Home Networking or Home Network. There are some really good simple networking guides in the XP help.
Here is a good web site
http://www.practicallynetworked.com/